1. Field of the Invention
The present invention relates to ventilation devices, and particularly to both ventilation devices having a nasal inserts and exhalation ports, and mask type ventilation devices, each having particular utility in various modes of therapy for obstructive sleep apnea as well as utility for continuous positive airway pressure (CPAP) devices, bi-level positive airway pressure (BiPAP) devices and non-invasive ventilation.
2. Description of the Related Art
Pressurized gas and ventilation devices designed to be worn on a user's head or face are utilized for a variety of purposes. These devices may be used to provide relief from respiratory ailments, such as sleep apnea, provide a conduit for aerosolized medicine, or non-invasively provide a user with an appropriate amount of gas, such as oxygen. These devices, however, can be disruptive to an activity the wearer seeks to perform and may be generally uncomfortable to the wearer. Additional problems arise with these devices because gas flow inside the mask or cannula is not optimized and may cause irritations associated with improper gas flow, such as excess noise.
The treatment of sleep apnea is a known field of use for pressurized gas devices. Sleep apnea is a potentially lethal affliction in which breathing stops recurrently during sleep. Sleep apnea may be of the obstructive type (sometimes known as the pickwickian syndrome) in which the upper airway is blocked in spite of airflow drive; the central type with decreased respiratory drive; or a mixed type. Breathing may cease for periods long enough to cause or to exacerbate cardiac conditions, and may be accompanied by swallowing of the tongue. Sleep apnea frequently results in-fitful periods of both day and night sleeping with drowsiness and exhaustion, leaving the patient physically and mentally debilitated.
In recent years it has been found that various forms of positive airway pressure during sleep can be an effective form of therapy for the apnea sufferer. Ventilation can be applied in the form of Continuous Positive Airway Pressure (CPAP) in which a positive pressure is maintained in the airway throughout the respiratory cycle, Bilevel Positive Airway Pressure (BiPAP) in which positive pressure is maintained during inspiration but reduced during expiration, and Intermittent Mechanical Positive Pressure Ventilation in which pressure is applied when an episode of apnea is sensed. Positive airway pressure devices have traditionally employed either a face mask which only covers the patient's nose, or nasal pillows as the interface between the ventilation device and the patient's airway. However, there are problems with both of these interfaces.
The face mask requires a harness, headband, or other headgear to keep the mask in position, which many patient's find uncomfortable, particularly when sleeping. The face mask must seal the mask against the patient's face, and may cause irritation and facial sores, particularly if the patient moves his head while sleeping, causing the mask to rub against the skin. Face masks are also position dependent, and may leak if the mask changes position with movement of the patient's head. The face mask applies pressure to the sinus area of the face adjacent to the nose, causing the airways to narrow, thereby increasing the velocity of flow through the airway, but decreasing the pressure against the nasal mucosal walls. This strips moisture from the mucosal wall during inspiration, thereby causing drying and a burning sensation. These factors will often result in the patient's removal of the mask and discontinuance of positive airway pressure therapy.
Nasal pillows are pillowed style nasal seals which are pressed against the inferior portion of the nares to close the nostril openings. Nasal pillows require a headband or harness to maintain the pressure, resulting in the same patient discomfort noted with face masks. Nasal pillows have about a 0.25″ internal diameter at the nasal entry port where the seal is made. Therefore, pressurized air must pass through a constricted port, increasing the velocity of airflow, with resultant drying and burning of the nasal airways. The narrowed interface diameter of the nasal pillows causes a pressure drop, which is directly proportional to the drop in the number of available air molecules within the closed system. It is the volume of air molecules at the area in the patient's throat where the apneic events appear that is needed to correct apnea. The narrower the airways or the internal diameter of the nasal interface, the lower the volume of air molecules that will be available and the greater the driving pressure that is required to meet the volume demand. An increase in driving pressure does not fully compensate for the loss in the number of air molecules available.
A further problem with existing ventilation devices is that the carbon dioxide bleed ports for venting exhaled gases are noisy on both nasal face masks and nasal pillows. The whistling noise that occurs while utilizing such devices can prove quite annoying to the patient, awakening the patient and causing the patient to discontinue use of the ventilation device.
Another problem associated with the carbon dioxide bleed ports is a lack of alternative sizes and shapes of bleed ports which may be necessary for a certain application or for the specific needs of a patient. Past examples of bleed ports have used only fixed-size singular bleed port or pairs of bleed ports that do not provide for the efficient and quiet exhaustion of gases, resulting in inefficient use and uncomfortable wearing by the user.
Previous mask-type devices, such as face masks, ventilators and ventilation masks, have also utilized bleed ports. These devices, which may fit over a user's mouth and nose or only a user's nose, typically have either a single port or a pair of ports on the mask. However, with these masks, the exhaled gases can create a significant amount of noise during the exhaustion or exhalation process, disturbing the user and potentially interrupting use of the device. Additionally, the location, size and amount of exhaust ports on standard mask-type ventilation devices do not allow for optimal exhaust gas flow in certain situations, nor do they allow for adjustments to be made to suit a particular patient's needs or requirements.
A number of devices have been proposed which include a ventilation interface for supplying gases to be inhaled, for collecting exhaled gases, or for mounting sensors for measuring or monitoring respiratory function.
U.S. Pat. Nos. 5,335,654 and 5,535,739, issued on Aug. 9, 1994 to Rapoport and Jul. 16, 1996 is to Rapoport et al., respectively, describe a CPAP system using a conventional nasal mask, the innovation comprising a flow sensor in the input line connected to a signal processor to determine the waveform of airflow, which is connected to a flow controller to adjust the pressure of airflow as required. U.S. Des. Pat. No. 333,015, issued Feb. 2, 1993 to Farmer et al. shows an ornamental design for a nasal mask. U.S. Des. No. 262,322, issued Dec. 15, 1981 to Mizerak, shows an ornamental design for a nasal cannula with a mouth mask.
U.S. Pat. No. 4,782,832, issued Nov. 8, 1988 to Trimble et al., discloses nasal pillows held in the patient's nose by a harness arrangement, the device having a plenum with two accordion or bellows shaped nipples for fitting against the nostril openings. U.S. Pat. No. 4,774,946, issued Oct. 4, 1988 to Ackerman et al., teaches a nasal and endotracheal tube apparatus for administering CPAP to infants, the nose tubes having a bulbous portion for seating in the pares of an infant and a headband with a VELCRO®, or substantially similar hook and loop fastener, closure for supporting the cannula and supply tubes.
U.S. Pat. Nos. 5,269,296, issued to Landis on Dec. 14, 1993, and U.S. Pat. Nos. 5,477,852 and 5,687,715, issued to Landis et al. on Dec. 26, 1995, and Nov. 18, 1997, respectively, describe CPAP devices for the treatment of sleep apnea with relatively stiff or rigid nasal cannulae or prongs surrounded by inflatable cuffs to retain the cannulae in the pares, but which also may be supplemented by an inflatable head harness to position the cannulae and hold them in place, the two cannulae being joined by a conduit having vent holes to vent exhaled air. U.S. Pat. No. 5,533,506, issued Jul. 9, 1996 to the present inventor, discloses a nasal tube: assembly in which the tubes are tapered, frustro-conical assemblies with a soft membrane over the distal tip and a washer at the base of the nasal tube to prevent the tubes from falling through a support bar connected to a harness, the nasal tubes forming a positive seal with the inside of the nostrils to prevent the escape of gases.
U.S. Pat. No. 5,682,881, issued Nov. 4, 1997 to Winthrop et al., shows a nasal cannula for CPAP therapy with cone shaped nasal prongs in which the cannula is secured to the patient's upper lip by adhesive tape strips. U.S. Pat. No. 4,915,105, issued Apr. 10, 1990 to Lee, teaches a miniature respiratory breather apparatus in which relatively stiff or rigid nasal tubes have elastomeric packings for sealing the tubes in the nares.
U.S. Pat. No. 5,429,125, issued Jul. 4, 1995 to Wagner et al., teaches a mask-style ventilation device for providing oxygen to a user in which there are no exhaust or exhalation ports. U.S. Pat. No. 5,586,551, issued Dec. 24, 1996 to Hilliard, teaches a mask-style ventilation device for providing oxygen and other gases to a user in which there are two fixed size exhaust ports.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a ventilation interface solving the aforementioned problems is desired.